The comment you are replying to is using commas correctly: it's partitioning off a clause of the sentence as a side phrase that can be removed, and the resulting sentence is a fully grammatically-correct sentence. If you really hate commas, you can replace the commas here with parentheses, but honestly, I prefer the commas here.
I agree with the parent that in formal written English, the comma would be incorrect—cf. the "In compound predicates" section in [0]. But I disagree that the sentence is hard to parse as a result, and I doubt many would think twice about it given that we're on an informal internet message board.
The comma is a soft pause. We do this all the time in spoken language in order to break up an otherwise potentially ambiguous or hard to understand utterance, but it is basically dialectal. In writing that purposeful pause because a comma.
You can then analyze when such pauses are used in formal language, and infer rules for their use. But those rules aren’t going to be 100% consistent, and a violation of those rules is not a grammatical error in the sense that subject-verb disagreement would be.
TL;DR you said “majority” not “every.” That distinction is key.
